Reactivation of oil decolorizing mediums



Apnl 5,` 1938. c, F. TEARS REACTIVATION OF OIL DECOLORIZING MEDIUMSFiled Aug. 4. 193e CLAUDE Ff TEARS' mvEN-roR AT ORNEY Patented Apr. 5,1938 I uNlrl-:oysrATEs PATENT OFFICE REACTIVATION F OIL DECOLORIZINGMEDIUMS` Claude F. Tears, Warren, Pa., assignor to The PetroleumyProcesses Corporation, Wichita, Kans., a corporation ofi'KansasApplication August 4, 1936, Serial No. 94,161

8 Claims. (Cl. 252-2) This invention relates to the reactivation 0fsolution of oil in the solvent the mixture is the mediums employed forthe deoolorizing 0f shown as passing through line 8 to a heater 9.lubricating oils and is a continuation in part of The heated solutionmay then be passed through the Tears application, Serial No. 679,073,Patent line I0 direct to the iilter II or it may iirst be 2,067,802,Jan. 12, 1937. passd by line Ill-I2 through cooler I3 and Theconventional method of reactivating thence by line I4-I0 to the filter,the cooling fullers earth and like decolorizing mediums is by thuseffected enabling operation at lower presroasting. The expense incurredin the transfer s'ure. Valves I5, I6, I1 in the lines connecting to andfrom the roaster and the resultant losses the heater and cooler and thelines'connecting lo are considerable. with the ilter enable such controlto be exercised 10 Special objects of this invention are to avoid and,if desired, the sending of the llow partly such expenses and lcsses andto get a greater through the heater and partly through the coolereiiciency in the reactivated material than has in series with theheater. been possible by such prior methods. It has been found that themost desirable These particular objects and other desirable filteringtemperature is in the neighborhood of 15 objects are attained in thepresent invention by v 125 F., but acceptable results can be obtainedthe novel features of invention hereinafter dewithin the temperaturerange of 60 F. to 200 F.' scribed, illustrated and broadly covered in thSince the solvent is normally gaseous, it is ClaimS- necessary tomaintain pressure on the entire 'The drawing accompanying and formingpart mixing and filtering system suflicient to keep 20 of thespecication illustrates diagrammatically the solvent in the liquidstate. 'I'his is effectedv one preferred embodiment of the invention,but it in the illustration by a regulatable valve 49 in will beunderstood that structure and steps of the flow line I0 leading to thelter, which maint-he process may be modied, as conditions retains adesired back pressure on the mixing, quire, all within the true intentand broad scope heating and cooling system and valve 44 in the 2'5 ofthe invention. discharge lino la from the bottom of the nner Theinvention involves reactivation of the demaintains a desired pressure inthe illter.

colorizing medium by color removing solvent. In The ltered ordecolorized oil solution passes the prior Tears application No. 679,073,above through line I8 to the still I9 through a heater referred to,trichlorethylene was disclosed as be- 20 where it is heated tovapor'ize` the solvent. 30 ing particularly eiective in vremovingcoloring The major portion of the solvent is vdistilled off matter, oil,or carbon from a propane treated in still I9 and leaving at the top byline 23 is conl clay and' for reactivating such clay. It has been densedin condenser 24 and under control of found that methylene chloride(dichlor-methane valve' 25 returned through line 26 to the storagelCHzClz'is especially effective as a color removtank 2. 35

ing solvent and reactivating agent. Chloroform Pressure of approximately200 pounds per (CHCla) also has been used with success. These, squareinch is maintained on the still by control as well as the general class,of the chlorinated of valve 25 and heat for distillation is shown ashydrocarbon compounds, are peculiarly eiective applied by means of aheating coil 41 inthe base solvents for color-removal and reactivation.of the still. From thebottom of the still the 40 To illustrate theprocess, reference is made to partially denuded, decolorized oil ows byline 2| the accompanying diagram, which is in the nato a stripper 48,which is provided with a heatture of a ow sheet showing basically thepering coil 50 and is operated at low pressure, for cclation method ofdecolorizing first ydisclosed in instance on the order of 15 pounds persquare 45 the above-identified earlier Tears application inch. At thispressure all the remaining solvent 45 and involving the ltering oflubricating oil in may be distilled ofi through line 5I, connectedsolution in a normally gaseous, liquefied hydroto the suction side ofthe compressor 32, which carbon. latter serves to compress the-solventvapor for In this particular illustration, the oil to be recovery bycondensation in the condenser 33.

decolorized is taken from storage tank I and the Back pressure ismaintained in the condenser by 60 normally gaseous liquefiedhydrocarbon, such as manipulation of vvalve 53 and the recoveredsolpropane, under pressure, and in the liquid state, vent in liquid formreturns to the solvent storis taken from a suitable holder 2, pumps 3and 4 age tank 2 through lines I4-26.' A valve 'I0 is conveying the sameunder pressure through lines shown provided in a bypass 'Il about thecom- 55 5 and 6 into a mixer l. To promotecomplete presser. 55

When the decolorizing clay becomes exhausted and therefore useless as adecolorizing medium, the oil is rst washed out of the clay by pumpingfresh solvent under pressure from pump 4 through line 29, with valve 28open and valve 21 closed, directly into the top of the iilter. Thisfresh solvent passes down through the clay and washes out the oilretained by the clay. This filter Wash is passed over through line I8 tothe still I9 for recovery of the solvent.

'Ihe next step is to remove the solvent from the clay for recovery. Thismay be accomplished by heating the bed of clay by means of the internalheater 30 and vaporizing the solvent through line 3| directly to thecondenser 33 by opening the compressor bypass 1l at the valve 10. Thisdistillation may be continued so long as solvent can bev thus removedand at the end of such timethe compressor bypass is closed at valve 10and valve 50a is opened to vent the lter to the suction side of thecompressor. In this operation all solvent is removed from the clay bylow pressure distillation. After all the solvent has been thus removed,the clay is ready for reactivation by Washing ,with the color-removingsolvent.

The color-removing solvent is transferred by pump 62 from tank 35through line 36 to the filter. Valve 44 at the bottom of the filter isclosed and valve 31 in the line 45 leading to the still 38 is opened sothat the solution of coloring matter in the color-removing solventpasses to still 38, vbeing heated on the way by heater 46. Additionalheat is supplied in the illustration by heater 46a in the base of thestill. As the colorremoving solvent is distilled off, the color-bearingconstituents are removed at the bottom.through line 39 and cooler 40.Such material may be diverted to a storage tank, not shown.

The overhead vapor from still 38 may be directed through line 63 tocondenser 56 to be condensed and returned through line 64 to tank 35, orit may be passed through the reflux condenser 51 to be condensed andreturned hot to the lter for the removal of additional coloring matter.When the reiiux condenser is used in this way it is preferable tohave aportion of the vapor stream passing through the nal condenser 56 andback to the color-removing solvent storage tank 35.

Washing with the color-removing solvent is continued until the streamfrom the base of the filter is colorless, indicating complete removal ofthe color-bearing constituents from the decolorizing medium. It thenbecomes necessary to recover the color-removing solvent. This may beaccomplished by dlstilling it from the decolorizing medium directly tocondenser 56 through the valved bypass 59 around the reflux condenser51, heat for such distillation being supplied by heating coil in thefilter.

Distillation of the color-removing solvent is continued until all suchsolvent is removed from the decolorizing medium. In some cases it may bedesirable to remove .the last traces of colorremoving solvent from thedecolorizing medium by Washing such medium with fresh, normally gaseousliqueed hydrocarbon from tank 2. When this washing step is employed theliquefied hydrocarbon solvent is passed on into still 38 from which itis distilled overhead through line 63-58 directly to condenser 33 byopening valve 60 and closing valve 6l. Experience has shown that only arelatively small amount of the colorremoving solvent is Washed out ofthe decolorizing medium by'this normally gaseous, liquefied hydrocarbonwash. The small amount thus removed may be accumulated in the base ofstill 38 and removed by distillation through condenser 56 when the still38 is next used for recovery of color-removing solvent.

Decolorizing medium, such as 30-60 mesh fullers earth may bereactivatedat least six times using methylene chloride in the manner described andthe reactivated clay has a relative eiiiciency of above as compared'with new fullers earth. This is considerably higher than the efficiencyof fullers earth reactivated under the present methods of roasting.

After about six reactivations under this invention the eiciency of thedecolorizing medium decreases rather rapidly. Apparently such suddendrop in decolorizing efliciency is due to failure of the methylenechloride to completely re- Amove all the color-'bearing compoundsretained by the decolorizing medium. To furthenuse the medium it thenbecomes necessary to employ a second color-removing solvent which willremove those compounds not removed by the methylene chloride. Adesirable second solvent for such purpose is a mixture of 50% benzol and50% methanol.

Alfter reactivating the decolorizing medium some five or six times withmethylene chloride, it may be washed with this second, benzolmethanolmixture to reactivate it for use again. In the illustration, thebenzol-methanol mixture is supplied from tank 65 and line (i6- 36, bypump 62 to, the filter and returned after recovery to the tank by line64-61.

The process has been described above in connection with `percolationfiltration of a solution of lubricating oil in normally gaseousliquefied hydrocarbon. While the use of normally gaseous liqueedhydrocarbon solvent is highly desirable ln the operation of the presentprocess, it isv not entirely essential and the reactivation need notnecessarily involve the Washing with normally gaseous liquefiedhydrocarbon solvent before and after washing with the, color-removingsolvent. Other oil solvents may be used for removal of oil from thefullers `earth and for the removal of the color-removing solvent fromthe fullers earth.

The present solvent reactivating process may be employed also forreactivation of contact ltering mediums, such as iine fullers earth, orsome of the chemically treated decolorizing clays. Such contactfiltering operations may be conducted With the oil in solution in anormally gaseous liqueed hydrocarbon solvent, in naphtha as a solvent,or the oil may be contacted hot without the use of any solvent. In allsuch contacting operations it is usual to filter out the contact clay in`a iilter press, the clay being retained on the lter plates. Aconvenient means of reactivating such contact clay under the presentinvention is to Wash it in place on the filter plates with thecolor-removing solvents here disclosed. The clay can then be dried inplace in the filter, or may be removed from the filter and driedelsewhere, being then ready for use again.

As an example of the effectiveness of the present method, ordinary, nefullers earth was used .for contactfiltering a solution of Pennsylvaniasteam-retined stock in naphtha at a temperature of F. with three poundsof the ne fullers earth per gallon of steam-reiincd stock in thesolution. This resulted ina color of 8 N. P. A. after the naphtha wasremoved from the deform until the color of the chloroform indicatedremoval of no more color constituents. vThis same clay was used ve timesafter such reactivation and under the same filtering conditions it wasfound that there was no distinguishable differences in the color of thenished oil from the ve fltrations.

'I'he present invention avoids the costly handling and transfer betweenthe filter and roaster and saves the losses heretofore occasioned bysuch handling. Furthermore, the emciency of the medium reactivated bythis solvent washing is much higher than the same medium reactivated bythe roasting. The invention may be practiced by relatively simpleadditions to and modification of present equipment. r

I claim:

1. 'I'he herein disclosed process of reactivatlng adsorbent decolorizingmedium, which comprises washing the same with methylene chloride.

2. The herein disclosed process of reactivating adsorbent decolorizingmedium,l which comprises washing the same with' methylene chloride and'thereafter washing said medium with a mixture 'washing the same with acolor-removing solvent of the chlorinated hydrocarbon class and thenwashing the medium with normally gaseous liqueed hydrocarbon whilemaintaining sufficient pressure to hold the normally gaseousliquefiedhydrocarbon in a liquid state.

5. The process of reactivating decolorizing medium, which compriseswashing the same with a color-removing solvent of the chlorinatedhydrocarbon class, then washing with a mixture of benzol and methanoland finally washing with a normally gaseous liquefied hydrocarbon underpressure suifcient to maintain the solvent in the liquid state.

6. 'Ihe process of reactivating decolorizing medium, which-compriseswashing the same with methylene chloride, washing with a benzolmethanolmixture, and then washing with a liquefied normally gaseous hydrocarbonunder pressure sufficient to maintain the solvent in the liquid state toremove traces of both previous washes.

7. The process of repeatedly reactivating adsorbent decolorizing medium,which comprises washing said decolorizing medium after each use withchlorinated hydrocarbon solvent until such washing fails'to restore thedecolo'rizing eiliciency of the adsorbent medium and then washing saidmedium with'a mixture of methanol and benzol, which will remove thecolor compounds irremovable by'the chlorinated hydrocarbon andthereafter washing with a liquefied normally gaseous hydrocarbon undersuflicient `pressure to maintain the same in a liquid state.

8. The process of reactivating decolorizing medium which compriseswashing it rst with a liqueed normally gaseous hydrocarbon underpressure suflicient to maintain the same in a liquid state, then washingwith a chlorinated hydrocarbon and thereafter washing with a liquefiednormally gaseous hydrocarbon under pressure suiiicient to maintain thesame in a liquid state.

' v CLAUDE F. TEARS.

